- Joined
- May 14, 2014
- Messages
- 2,280
- Location
- Southwest Kootenays BC
- Tagline
- No such things as bad days, just bad moments
I hope to dip into the Trough of Knowledge yet again.
This relates back to the NAD 502 CD player in which I wanted to substitute LED's to backlight the LCD display. I got that sorted out but induced a couple of subsequent problems. The first was that I killed power to the laser assembly /spindle motor. This could have been because I left the power on when soldering the lamp leads. There was a spark when the soldering iron tip contacted the chassis. After that, there was no movement of any kind from the laser pickup and the spindle motor didn't turn.
Yes, leaving the power on was stupid but it gets better.
I unfastened the board and not thinking because the power was still on, let it sit foil side down on the metal chassis as I started fumbling around looking for the point where the laser/motor was getting power. Something shorted and caused a 16v 100uF capacitor (C517) to explode. I replaced it but both of the two fuses blow on power up so obviously there was more damage. There is an NE5532N opamp (Q204) that I think was involved and will be getting some of those this afternoon. I also suspect IN4002 diodes were affected but I should be able to get those at the same time.
There is another semiconductor (Q507) I've never needed to concern myself with before that seems to be the "brains" behind power distribution and I think it's cooked. The part number is TA7256 or alternately, KA9256. My ability to read data sheets is feeble at best and I have difficulty enough with NPN/PNP transistors. This device is more complex and it baffles me. If anyone knows these things well enough to recommend a substitute, I would like to try replacing it.
This relates back to the NAD 502 CD player in which I wanted to substitute LED's to backlight the LCD display. I got that sorted out but induced a couple of subsequent problems. The first was that I killed power to the laser assembly /spindle motor. This could have been because I left the power on when soldering the lamp leads. There was a spark when the soldering iron tip contacted the chassis. After that, there was no movement of any kind from the laser pickup and the spindle motor didn't turn.
Yes, leaving the power on was stupid but it gets better.
I unfastened the board and not thinking because the power was still on, let it sit foil side down on the metal chassis as I started fumbling around looking for the point where the laser/motor was getting power. Something shorted and caused a 16v 100uF capacitor (C517) to explode. I replaced it but both of the two fuses blow on power up so obviously there was more damage. There is an NE5532N opamp (Q204) that I think was involved and will be getting some of those this afternoon. I also suspect IN4002 diodes were affected but I should be able to get those at the same time.
There is another semiconductor (Q507) I've never needed to concern myself with before that seems to be the "brains" behind power distribution and I think it's cooked. The part number is TA7256 or alternately, KA9256. My ability to read data sheets is feeble at best and I have difficulty enough with NPN/PNP transistors. This device is more complex and it baffles me. If anyone knows these things well enough to recommend a substitute, I would like to try replacing it.
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